A proportional variable force solenoid control valve that is relative low in cost to manufacture and compact in size while maintaining substantially linear proportional fluid control is described in the Najmolhoda U.S. Pat. No. 4,988,074 issued Jan. 29, 1991, of common assignee herewith. The patented proportional variable force solenoid control valve comprises an outer steel solenoid housing and a cast aluminum valve member housing joined together mechanically such as by tabs on the steel solenoid housing being crimped about regions of the aluminum valve member housing.
The proportional variable force control valve includes a ferromagnetic (e.g. steel) armature suspended by low spring rate springs at opposite ends of the armature within the bore hole of a coreless solenoid bobbin for reciprocable movement between positions corresponding to a closed valve position and fully open valve position in response to applied electrical current to an electromagnetic coil. The position of the armature is controlled by balancing the variable force of an electromagnetic field of an electromagnetic coil and the force of the magnetic field of a permanent ring magnet against the force of a compression coil spring which biases the valve toward the closed position of the valve. The electromagnetic coil, bobbin and armature reside in the steel solenoid housing in a manner that the steel housing provides a concentration of flux of the electromagnetic field at a steel fluid control valve fixed on the armature. The fluid control valve fixed on the end of the armature moves relative to a valve seat disposed in the aluminum valve housing to communicate a fluid inlet to fluid exhaust ports so as to regulate fluid pressure at fluid control ports in a manner proportional to the magnitude of applied electrical current.
A commercially manufactured version of the aforementioned patented proportional variable force solenoid fluid control valve has been modified to include a stainless steel ball valve and a separate stainless steel valve seat insert pressed in the nozzle. The ball valve is captured in a stainless steel cage press fit in nozzle between the valve seat insert and a rod-like, cylindrical shaped steel armature that moves relative to the valve seat in a manner proportional to the magnitude of electrical current applied to the electromagnetic coil. As the armature moves relative to the valve seat to open the valve, the ball valve is caused to follow the end of the armature by virtue of fluid pressure in the valve member housing and confinement in the ball valve cage in the bobbin. The fluid inlet is communicated to fluid exhaust ports by opening of the ball valve so as to regulate fluid pressure at fluid control ports in a manner proportional to the magnitude of electrical current applied to the coil.
A spool valve is disposed in the valve member housing for providing a two stage, high flow capability operation wherein pressurized fluid supplied to the inlet port initially is directed to bypass the control ports and flows to an end of the spool valve to move it from a zero fluid flow spool position to a maximum fluid flow spool position relative to the control ports as determined by the cracking pressure preset for the ball valve by adjustment of the coil spring force. Thereafter, a second stage of operation involves controlling the fluid flow through the control ports by moving the spool valve between minimum and maximum flow spool positions by armature movement in a manner proportional to the magnitude of electrical current to the coil. Such proportional variable force solenoid control valves commercially manufactured to-date are operably mounted to a cast aluminum transmission body or case by a clamp plate, bolt, or both engaging an outer nozzle groove.
An object of the present invention is to provide an improved proportional variable force solenoid fluid control valve of the type described hereabove wherein construction of the solenoid and valve components is further simplified while maintaining substantially linear proportional fluid control.
Another object of the present invention is provide an improved proportional variable force solenoid control valve having a common housing for the solenoid and the valve member components that can be inserted in a transmission body or case as a unit and retained in operative position by a simple plate or the like.
Still a further another object of the invention is to provide an improved proportional variable force solenoid control valve having a simplified armature suspension structure for positioning the armature within the bore hole of the solenoid bobbin for reciprocable movement with a low spring rate spring at only one end of the armature while maintaining linear proportional fluid control.
Still a further object of the present invention is to provide an improved proportional variable force solenoid control valve having an elastomeric ball valve and ball valve seat molded on the bobbin to provide improved performance (e.g. reduced resonance in fluid pressure regulation) at low line pressure and high temperature operation to maintain linear proportional fluid control.
Still an additional object of the present invention is to provide a simplified proportional variable force solenoid control valve that eliminates the need for a permanent ring magnet by virtue of employing a permanent magnet armature suspended for reciprocable movement in the bore hole of the electromagnetic coil without an air gap so as to maintain substantially linear proportional control of fluid pressure.
Still another object of the invention is to provide a fluid control device for a shift point of an electronic transmission wherein a proportional variable force solenoid control valve and a transmission spool valve operably associated are disposed in a common housing to provide regulated fluid pressure to smooth gear shifting at a particular shifting point of the transmission.